$namespace: 'rt' !default;
$block-sel: '-' !default;
$elem-sel: '__' !default;
$mod-sel: '--' !default;

// --------------------------------------- BEM start-------------------------------------
@mixin block($block) {
  $b: #{$namespace + $block-sel + $block};
  .#{$b} {
    @content
  }
}

@mixin elem($elem) {
  $selector: &;
  @at-root {
    #{$selector + $elem-sel + $elem} {
      @content
    }
  }
}

@mixin mod($mod) {
  $selector: &;
  @at-root {
    #{$selector + $mod-sel + $mod} {
      @content
    }
  }
}

// --------------------------------------- BEM end-------------------------------------